Lens component and light emitting device

Abstract

A lens component disperses light from a source having a distribution characteristic in which luminosity becomes smaller according to distance from the optical axis. The component includes an incidence portion at a source position struck by light from the source and guiding portions branching from the incidence portion and extending radially from the source position. Each guiding portion includes a basal end portion joined to the incidence portion, emission end portion emitting light away from the source, and reflection surface guiding light that struck the basal end portion while performing internal reflection. The incidence portion and guiding portions form a light distribution structure arranged so that a ratio of luminosity in a direction making a predetermined angle with the optical axis with respect to luminosity in the axial direction in light emitted from the structure is larger than a corresponding ratio in the source's distribution characteristic.

The invention claimed is: 
     
       1. A lens component that disperses light from a light source having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis, the lens component comprising:
 a light incidence portion that has an incidence surface stricken by light from the light source placed at a predetermined light-source position; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 wherein the incidence surface includes a plurality of incidence regions that are disposed so as to face the basal end portions of the plurality of light guiding portions, respectively, and that gather light from the light source or convert light from the light source into parallel light and then let the light enter a corresponding one of the light guiding portions, 
 wherein the plurality of incidence regions include a first incidence region, and a second incidence region that is disposed farther from the optical axis than the first incidence region and that is wider than the first incidence region. 
 
     
     
       2. The lens component according to  claim 1 , wherein the plurality of light guiding portions include:
 a first light guiding portion; and 
 a second light guiding portion that is disposed farther from the optical axis than the first light guiding portion and that is stricken by light having a quantity of light equal to a quantity of incident light onto the first light guiding portion from the light source. 
 
     
     
       3. The lens component according to  claim 2 , wherein the first light guiding portion and the second light guiding portion each have a pair of light-guide reflection surfaces, and the second light guiding portion is larger than the first light guiding portion in an interval between the pair of light-guide reflection surfaces. 
     
     
       4. The lens component according to  claim 1 , wherein, in a plane that includes the optical axis and that traverses the plurality of light guiding portions, an angular range of the second incidence region faced from the light-source position is wider than an angular range of the first incidence region faced from the light-source position. 
     
     
       5. The lens component according to  claim 1 , wherein the plurality of light guiding portions include at least one light guiding portion in which an angle that light emitted from the emission end portion makes with the optical axis is larger than an angle that the light makes with the optical axis when the light enters the light incidence portion. 
     
     
       6. The lens component according to  claim 1 , wherein the emission end portions of the plurality of light guiding portions emit light at mutually equal quantities of light. 
     
     
       7. A lens component that disperses light from a light source having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis, the lens component comprising:
 a light incidence portion that has an incidence surface stricken by light from the light source placed at a predetermined light-source position; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 wherein the emission end portions of the plurality of light guiding portions are disposed in the plurality of emission regions, respectively, that are set to be away from each other so as to evenly divide a predetermined angular range with respect to a circumferential direction that centers on the light-source position and that is along a plane including the optical axis. 
 
     
     
       8. A lens component that disperses light from a light source having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis, the lens component comprising:
 a light incidence portion that has an incidence surface stricken by light from the light source placed at a predetermined light-source position; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 wherein the emission end portions of the plurality of light guiding portions emit light in a plurality of emission directions, respectively, that evenly divide a predetermined angular range with respect to a circumferential direction that centers on the light-source position and that is along a plane including the optical axis. 
 
     
     
       9. A lens component that disperses light from a light source having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis, the lens component comprising:
 a light incidence portion that has an incidence surface stricken by light from the light source placed at a predetermined light-source position; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 wherein the plurality of light guiding portions have a plate shape that extends in parallel with a straight line that is perpendicular to the optical axis and that passes through the light-source position, and the emission end portion has a convex curved part that protrudes in a direction receding from the light-source position. 
 
     
     
       10. A light emitting device comprising:
 a light source placed at a predetermined light-source position and having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis; and 
 a lens component that disperses light from the light source, the lens component including: 
 a light incidence portion that has an incidence surface stricken by light from the light source; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 wherein the light source includes a pair of light sources that share the optical axis and that emit light in mutually opposite directions. 
 
     
     
       11. The light emitting device according to  claim 10 , further comprising a translucent cover that is disposed outside the lens component and that has a diffusing portion that diffuses light striking from the lens component. 
     
     
       12. The light emitting device according to  claim 11 , wherein the light incidence portion, the plurality of light guiding portions, and the diffusing portion form a light distribution structure, and
 the light distribution structure is formed so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in the direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source. 
 
     
     
       13. The light emitting device according to  claim 10 , wherein
 the plurality of light guiding portions include: 
 a first light guiding portion; and 
 a second light guiding portion that is disposed farther from the optical axis than the first light guiding portion and that is stricken by light having a quantity of light equal to a quantity of incident light onto the first light guiding portion from the light source, and 
 the first light guiding portion and the second light guiding portion each have a pair of light-guide reflection surfaces, and the second light guiding portion is larger than the first light guiding portion in an interval between the pair of light-guide reflection surfaces. 
 
     
     
       14. The light emitting device according to  claim 10 , wherein the incidence surface includes a plurality of incidence regions that are disposed so as to face the basal end portions of the plurality of light guiding portions, respectively, and that gather light from the light source or convert light from the light source into parallel light and then let the light enter a corresponding one of the light guiding portions. 
     
     
       15. The light emitting device according to  claim 10 , wherein the plurality of light guiding portions include at least one light guiding portion in which an angle that light emitted from the emission end portion makes with the optical axis is larger than an angle that the light makes with the optical axis when the light enters the light incidence portion. 
     
     
       16. A light emitting device comprising:
 a light source placed at a predetermined light-source position and having a light distribution characteristic in which luminosity becomes smaller according to a distance from an optical axis; and 
 a lens component that disperses light from the light source, the lens component including: 
 a light incidence portion that has an incidence surface stricken by light from the light source; and 
 a plurality of light guiding portions that branch from the light incidence portion and that extend radially with respect to the light-source position, 
 each of the light guiding portions including: 
 a basal end portion joined to the light incidence portion; 
 an emission end portion that emits light outwardly away from the light source; and 
 a light-guide reflection surface that guides light that has stricken the basal end portion from the light incidence portion to the emission end portion while performing internal reflection, 
 the light incidence portion and the plurality of light guiding portions forming a light distribution structure, 
 the light distribution structure being arranged so that a ratio of luminosity in a predetermined direction making a predetermined angle with the optical axis with respect to luminosity in a direction along the optical axis in light emitted from the light distribution structure is larger than a corresponding ratio in the light distribution characteristic of the light source, 
 the light emitting device further comprising a substrate having a pair of principal surfaces on which the pair of light sources are mounted, respectively, 
 wherein the lens component has: 
 the pair of light-source positions corresponding to the pair of light sources; 
 a tubular external shape extending in parallel with a straight line that is perpendicular to the optical axis and that passes through the light-source position; and 
 a light-source containing portion that contains the pair of light-sources so as to place the pair of light-sources at the pair of light-source positions, respectively, through the substrate, and 
 wherein the plurality of light guiding portions are disposed such that each group consisting of ones of the plurality of light guiding portions surrounds each light source. 
 
     
     
       17. The light emitting device according to  claim 16 , wherein a plurality of the lens components are connectable together along an axis of the tubular shape, and the plurality of substrates are disposed at the light-source containing portions of the plurality of lens components, respectively,
 the light emitting device further comprising a connector by which the substrates disposed at the light-source containing portions, respectively, of the lens components contiguous to each other are electrically connected to each other. 
 
     
     
       18. The light emitting device according to  claim 17 , wherein the substrate is disposed such that the pair of principal surfaces follow a direction in which the axis of the tubular shape of the lens component extends while being offset from the axis, and the connector is mounted on a first principal surface that is one of the pair of principal surfaces and that is on a side closer to the axis. 
     
     
       19. The light emitting device according to  claim 18 , wherein a distance to the incidence surface from the light source mounted on the first principal surface is longer than a distance to the incidence surface from the light source mounted on a second principal surface that is one of the pair of principal surfaces and that is on a side farther from the axis. 
     
     
       20. The light emitting device according to  claim 16 , wherein the lens component includes divided pieces obtained by dividing the tubular external shape into a plurality of pieces in a circumferential direction, and forms a tubular external shape by joining the divided pieces together in the circumferential direction. 
     
     
       21. The light emitting device according to  claim 16 , wherein
 the plurality of light guiding portions include: 
 a first light guiding portion; and 
 a second light guiding portion that is disposed farther from the optical axis than the first light guiding portion and that is stricken by light having a quantity of light equal to a quantity of incident light onto the first light guiding portion from the light source, and 
 the first light guiding portion and the second light guiding portion each have a pair of light-guide reflection surfaces, and the second light guiding portion is larger than the first light guiding portion in an interval between the pair of light-guide reflection surfaces. 
 
     
     
       22. The light emitting device according to  claim 16 , wherein the incidence surface includes a plurality of incidence regions that are disposed so as to face the basal end portions of the plurality of light guiding portions, respectively, and that gather light from the light source or convert light from the light source into parallel light and then let the light enter a corresponding one of the light guiding portions. 
     
     
       23. The light emitting device according to  claim 16 , wherein the plurality of light guiding portions include at least one light guiding portion in which an angle that light emitted from the emission end portion makes with the optical axis is larger than an angle that the light makes with the optical axis when the light enters the light incidence portion.